Phospholipid compositions have conventionally been produced from natural phospholipid-containing substances such as egg yolks, soybeans or bacteria. Methods for producing phospholipid compositions vary depending upon the source of phospholipids to be used. For example, in the case where egg yolk is used as the source of phospholipids, the phospholipid composition is produced, in general, by extracting phospholipid components from dried egg yolk by allowing an alcohol to act on it, and then removing the alcohol from the extract. In this process, neutral lipids are removed from the above-obtained phospholipid composition ordinarily by treating it with acetone for purification, as needed.
The phospholipid composition thus obtained has widely been used as an emulsifier for producing pharmaceuticals, cosmetics, foods, and the like. In these fields, those emulsions (e.g., fat emulsions) produced by using the phospholipid composition as an emulsifier are usually put into use after subjected to heat sterilization. It is therefore necessary that the emulsions can stand heat sterilization; that is, they are required not to be demulsified easily during heat sterilization. Moreover, with respect to the lowering of the pHs of the emulsions, which is often caused while the emulsions are sterilized by heating, the degree of lowering is required to be small. However, conventional phospholipid compositions are not necessarily satisfactory from this point of view.
A primary object of the present invention is therefore to provide a novel phospholipid composition capable of giving an emulsion which is free from the aforementioned problems.